Commercial passenger carrying airplanes commonly have storage or compartment structures (frequently referred to by the generic name “monuments”) installed on the aircraft. These structures are used in a variety of ways, such as storage of clothing and other passenger belongings, electronic entertainment centers, sleeping quarters for the officers and cabin crew, purser work stations, bar units, lavatories, and galleys used to provide in-flight catering meal service to the passengers. Traditionally, these monuments have been manufactured using multi-layered lightweight assemblies known as “sandwich panels” of Nomex® or Kevlar® cores, with resin pre impregnated fiberglass skins forming the surface. Other types of composite panels are manufactured with foam, thermo-plastic or metallic core materials and with plastic or metallic outer skins. Aircraft monuments may alternatively be constructed entirely from flat sheet materials that are pre manufactured in a process using a multi-layer temperature controlled press, and/or from molds using an autoclave to provide both temperature and pressure for curing of the panel, part or section.
Following manufacture, these parts or sections have to undergo additional “pre or post processing” where they may be trimmed, cut and/or formed into the parts necessary to construct the monument. They will also commonly undergo secondary operations to have fixing points and/or locating holes installed in the form of “inserts” or “bobbins.” In the case of the former, they provide a means of attaching items to the panel, and rely on the injection of an adhesive around the fixing to form a plug that resists being pulled out through the skin when a load or force is applied to it. In the case of the latter, a through hole is provided for fixings that would otherwise damage the panel.
Items attached to the panels include wiring looms and electrical components, plumbing hoses, pipes and components, ventilation and air extraction duct, hose and component mountings, décor panels, hinges, back stops, galley insert equipment interfaces, access panels, ducts, sliders and draw runners, electronic entertainment devices, grilles, and general equipment retainers.
After the preparatory stages are complete, the monument is constructed by assembling the various parts, either by bonding the flat panels together to form a rigid structure with viscous liquid adhesives, or by combining the flat panels with pre manufactured (e.g. pre cured) molded parts to form the basic structure. These molded sections or flat panel sub-assemblies may also remain as removable (i.e. bolt on/bolt off parts). Likewise, adhesive bonded flat panels forming sub-assemblies or modules may be bolted together to form the complete structure.
Basic construction in all cases involves a post composite panel manufacturing process that relies on bonding using liquid adhesives for the panels forming the structure itself, the fixing points, through holes and mountings and/or the sub-assemblies, modules and moldings themselves. Further, secondary operations attaching various loose metallic and non-metallic parts to the basic structure, together with electrical, water and air systems are then undertaken. These separate processes add significantly to the cost and construction time, and require a high level of expert knowledge and operator skill.
Another issue with the current monument construction is the need for reinforcement. To reinforce a given monument structure, “C,” “U,” “H,” “F” and right angle as well as other shapes of section aluminum extrusions are commonly bonded to the edges of the panels for stiffness. Where local re-enforcement of the structure is required (for load bearing purposes), flat sheets of aluminum, typically 1/32″ to ⅛″ thick, are bonded to the panel to transfer the effects of localized stress to portions of the structure with higher load bearing capabilities. This type of additional localized reinforcement is commonly called a “doubler.” This practice adds significant weight to the Monument and requires another manufacturing process, adding the cost.